Extruders and processes for extruding plastic material and forming pellets there from have been known and used for some time. Once plastic pellets have been extruded, they are commonly placed into a fluid stream, such as water. The fluid stream serves to cool the plastic pellets and allow them to form, while also carrying the plastic pellets to subsequent steps in the process. Such an extruder or pelletizer may be referred to as an underwater pelletizer, water ring pelletizer or other form.
U.S. Pat. No. 4,529,370 illustrates one example of a conventional underwater pelletizer. Another example of a conventional underwater pelletizer is shown in U.S. Pat. No. 5,059,103.
One subsequent step in the pelletizing process is drying the plastic pellets. However, in order to dry the pellets, the pellets must be separated from the fluid stream. Conventional centrifugal pellet dryers can be seen in U.S. Pat. Nos. 4,565,015, 5,611,150, and 5,987,769, as well as International patent application publication WO2002/031420. Conventional centrifugal pellet dryers operate to separate the pellets from a slurry of pellets and water, but often cause deformation of the pellets or produce plastic remnants that may become imbedded in the parts of the pellet dryer machinery and often must be thoroughly cleaned out to avoid contaminating subsequent batches of pellets.